1. Field of the Invention
The present invention relates to a method of binding sulfur and other impurities during the combustion of fuels that contain such impurities. The fuel is burned in an annular burner flame that has an internal recirculation zone. An additive in the form of an aqueous suspension is sprayed into the combustion chamber via at least one two-component atomizing nozzle, and the additive is mixed with the gases of the flame under optimum reaction conditions. The present invention also relates to an annular burner for carrying out such a method, with at least one two-component atomizing nozzle being associated with the burner for introducing an aqueous additive suspension into the region of the flame.
2. Description of the Prior Art
A method of the aforementioned general type is known from U.S. Pat. No. 4,331,638, Michelfelder, dated Apr. 3, 1984, which belongs to the assignee of the present application. With this known method, the additive is injected into the combustion chamber via a number of nozzles distributed about the periphery of the burner. This forms a mist that surrounds the burner flame, with the additive diffusing into the flame from the mist.
German Offenlegungsschrift No. 19 02 504 discloses a method where the additive, in the form of an aqueous suspension, is sprayed into the burner flame at right angles to the blast of the flame. This leads to relatively unfavorable reaction conditions for the binding of SO.sub.2. In particular, the mixing rate required for a high degree of binding is not achieved in the flame temperature range that is favorable for the binding reactions.
U.S. Pat. No. 4,440,100 Michelfelder et al dated Apr. 3, 1984, which also belongs to the assignee of the present application, discloses injecting into the combustion chamber, from below, and at specified locations independent of the burner, additives in the form of pulverous materials, such as calcium carbonate, magnesium carbonate, dolomite, and reactive oxide and hydroxide compounds. In this known method, the additive is first introduced into recirculation flows that are within the system and are closed, and due to locally different pressure conditions in the combustion chamber are formed in the latter below the burner.
An object of the present invention is to provide a method, as well as an annular burner for carrying out this method, whereby it is possible to achieve a particularly favorable binding of noxious materials.